Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

E39 (1997 - 2003) The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

Look at this I had 15 miles of range and I forgot to fill up and had to work in the morning. Right after work I filled up. I thought my tank was 18.5 gallons or is that UK gallons. Wouldn't this be impossible unless they are ripping people off.

The only way to know for sure is to start with an empty tank and fill it...but not even completely empty. You just want it to be empty to the point of all useable fuel being out of it. Unuseable fuel is a certain residual amount that cannot be pumped to the engine.
Did the pump have a recent sticker from your state weights and measurements division?
If you're really suspicious, you can always call that state agency and ask them to check it out.

I've heard that numerous times on these forums, I really don't think it makes much difference. As long as there is fuel running through the pump that should help to cool it from the inside out. Myself and many others I know always wait till empty to fill up, which for me was about every 2.5 days for a few years. I've never had a fuel pump fail. I think when it's their time to go, they go., regardless of refueling habit.

I think that it does make a difference and completely agree with CN90. The pump is only cooled by fuel, why put unnecessary stress on it? Not only that but you risk clogging your filter with the crud at the bottom of the tank.

The mileage saving you might get by running "light" is so small as to be insignificant. But to each his own.

I think that it does make a difference and completely agree with CN90. The pump is only cooled by fuel, why put unnecessary stress on it? Not only that but you risk clogging your filter with the crud at the bottom of the tank.

The mileage saving you might get by running "light" is so small as to be insignificant. But to each his own.

It still
has fuel running through it, that's sufficient to cool it.

If I filled at a quarter tank I'd basically live at the gas station. Had nothing to do with mileage, I'd fill her all the way up and drain her down.

Fuel pumps fail, that's life. I think someone hypothesized that it was due to low level and it spread across the interwebs like those things do. Has anyone done a study of a fuel pump submerged in fluid while pumping and one constantly pumping fluid but in the open?

If it were running dry, yeah it would over heat the motor. But, as long as fluid is moving through the pump it should be fine.

Quote:

Originally Posted by Nline6

DING DING DING... Why wait? your always going to use the fuel. Whats the point of risking overheating the hump or sucking up sludge, oh ya running out of gas...

Not to be rude but im a little surpised at how silly the question is,,

Now im concerned for your safety,, You keep a extra 2.5 gallons in your trunk ????

That is truly a dumb idea,,,

How is that dangerous? Its protected by the spare tire. You know you're carrying 19 gallons in your car. All I'm saying is that its just as safe as a gas tank in your car.

In New England with really cold weather. 2.5 gallons can save your life. Ever since the Halloween Blizzard when the gas stations ran out of gas and no power for 10 days. I decided to keep extra 60 miles of range in the trunk.

I typed /gasoline in the bestlinks and it came up with this, among many others:

- How large is the fuel tank and reserve in the E39 (1) & what gasoline to use (1) & how much gas should be left to cool the fuel pump (1) & how to siphon the fuel out of the tank (1) & what is the cost differential between 87 & 91 octane AKI (1)